The fragile cease-fire between Ukraine and pro-Russian separatists in the eastern part of the country is threatening to collapse. NATO officials say they've seen more Russian troops streaming across the border.

An analyst for the BBC isn't quite ready to say the cease-fire has collapsed yet, writing instead: "The question now is whether this is just a re-run of events in the summer or does a more significant clash beckon, perhaps one where the Kremlin may decide — in its terms — to teach the Ukrainians a military lesson."

Either way, there's no official word on the status of the cease-fire. According to The Daily Beast, rebels are hoping to have another round of peace talks with the Ukrainian government later this month.